Controlling snails, slugs key to fighting rat lungworm

Experts share tips with more than 100 in Haiku

Colleen Uechi

Staff Writer

cuechi@mauinews.com

Cynthia Nazario-Leary

HAIKU — Controlling snail and slug populations is one of the most important steps in fighting the spread of rat lungworm disease, health and agricultural experts said Monday evening during a meeting at the Haiku Community Center.

Experts shared tips with more than 100 residents on how to hunt for slugs and snails, protect gardens and catchment tanks and take extra precautions with raw foods.

Rat lungworm is caused by a parasitic worm that attacks the brain and spinal cord. It causes a rare type of meningitis, and victims have said that it started with flu-like symptoms and mushroomed into terrible pain throughout their bodies.

Since the state Department of Health reported six confirmed rat lungworm cases on Maui this year, with three under investigation, both government officials and residents have grown concerned at the higher-than-usual number and are eager to take action.

Holding up a bucket, a pair of tongs and gloves, Cynthia Nazario-Leary of the University of Hawaii College of Tropical Agriculture and Human Resources described to the crowd how to hunt for slugs. The invasive semi-slug is a notorious carrier of the parasite. It feeds on the feces of rats that host the worm. Humans can get infected by consuming raw produce or water contaminated by the slug. They can also get it from eating raw or undercooked snails, slugs, prawns and freshwater crabs.

Lorrin Pang

“The main thing you want to do is, you’ve got to think like a snail,” Nazario-Leary said. “They like to live in dark, moist places. Those are the places you want to focus on. You want to find out where they’re living on your property.”

Nazario-Leary told residents to check under boards and pots. Snails and slugs like to crawl underneath objects and cling to the top. They also come out in the evenings, so Nazario-Leary recommended hunting for them at night.

One of the best methods for controlling slugs and snails is “hand-picking,” she said. Residents should put on gloves and take a pair of tongs and a bucket labeled especially for this purpose. The captured slugs and snails should be submerged in a saline solution — 7 cups of water and 1 cup of salt — for 48 hours, to kill both the creatures and the parasites. Once they’re dead, they should be double-bagged in black trash bags and thrown out.

Nazario-Leary said there was a taro farmer in Hana who spent an hour and a half harvesting slugs and snails from his field one night. The next day it only took him 10 minutes.

“You can make a significant reduction in slugs and snails just by picking them up,” she said.

Lissa Fox Strohecker

Snails and slugs love succulents and leafy greens like lettuce, basil, broccoli and cabbage, so residents should take steps to protect their gardens, she added. She suggested irrigating in the daytime, so that gardens have time to dry out and won’t attract snails and slugs. The crops most at risk can be placed in a snail- and slug-free zone, protected with traps and barriers. Copper mesh and copper tape are most effective, because slugs pick up electrical charges as they cross and would rather avoid it, said Nazario-Leary, who recommended a 4-inch-wide barrier.

Dog and cat food also attracts slugs and snails, so pet dishes should be removed at night. Baits are also an option. Iron phosphate is labeled for organic use and safe around pets and kids.

The same steps — barriers, traps and constant inspections — should also be taken to protect catchment tanks, she said.

“There is no silver bullet,” she said. “I really recommend doing these techniques or a combination of them to make your garden as snail- and slug-free as you can.”

As for washing raw produce, Lynn Nakamura-Tengan, also with UH-CTAHR, encouraged people to continue steps they may already be taking — washing hands before touching food, and double rinsing with clean, running water. If someone has a cut, it should be covered with gloves.

“Even if you don’t see (anything), rub anyway,” she said.

Cooking food up to 165 degrees Fahrenheit, or freezing for 48 hours, can also kill the parasite.

Vinegar doesn’t work in rinsing, and in fact may irritate the slug and cause it to release the parasite, added Dr. Lorrin Pang, Maui County District health officer. Pang also encouraged people to see their doctors if they suspect they have any symptoms of the disease.

Lissa Fox Strohecker, public relations and education specialist for the Maui Invasive Species Committee, asked people to help identify and report semi-slugs. If people think they’ve found a semi-slug, they should take a photo and send it to MISC, she said.

“We’re probably at the beginning of the spread of the semi-slug population,” Strohecker said. “That can help us find hot spots in the community.”

Semi-slugs look somewhat between a snail and a slug due to their small external shells. Fully grown, the slugs are 2 inches long, according to MISC manager Adam Radford. The semi-slugs are an introduced species.

A number of parents at the meeting were concerned about their kids being able to run and play outside. Haiku resident Shine Tretter said she would love to be able to lay her 8-month-old son in the grass, but just doesn’t feel safe doing so these days. She and her family have a vegetable garden and plenty of slugs on property.

“I’m so bummed,” Tretter said. “It’s definitely disappointing and scary to have to be so cautious about just eating from the gardens and walking barefoot — all the things we love to do.”

Warren Watanabe, a Haiku resident and executive director of the Maui Farm Bureau, said while it appears the slug is concentrated in Hana, “it is a concern” that it could spread to Haiku, where wet climate and abundant farms could be attractive to slugs. He said that farmers, distributors, residents and government need to work together to keep the slugs at bay.

“We all share the responsibility,” said Watanabe, a retired farmer.

With the recent rise of rat lungworm cases, many are worried about “farmers losing their market.” Farmers are working with local officials to create a plan that will reassure the public that farmers are taking the necessary steps to control rat and slug populations, Watanabe said.

“Our biggest concern is the reaction of consumers saying they’re not going to buy local produce,” Watanabe said. “We need to assure the public that farmers are using best management practices. They understand the risks.”

For more information, visit health.hawaii.gov/docd/files/2015/07/angio-fact-sheet-20150716.pdf or cdc.gov/parasites/angiostrongylus/index.html.